The 8-Vestigial Side Band (VSB) method, which is a Digital Television (DTV) broadcasting standard adopted by the North America and Korea, hardly provides indoor and mobile reception performance desired by broadcasting companies.
To solve the problem, the Advanced Television System Committee (ATSC) has collected suggestions for improving the DTV reception performance and developed a DTV transceiving system using a dual stream structure. The present invention provides a trellis coding searching method which is used to generate robust stream in the DTV transceiving system using a dual stream structure. Conventional technologies and search algorithms search only for an optimal single stream codec. When the single stream codec search algorithm is used to search for an optimal dual stream codec, it cannot find out an optimal codec due to missing of a free distance computation termination condition that appears only in dual stream. The present invention provides the free distance termination condition to search for an optimal dual stream codec.